Semiconductor devices such as a memory and a microcomputer that are used for a computer or the like are manufactured by repeatedly executing transfer processes such as an exposure process, a lithographic process, and an etching process on a pattern such as, a circuit formed on a photomask. In the process of manufacturing the semiconductor devices, the yield of the semiconductor devices is significantly influenced by whether the results of the lithographic process, the etching process and other processes are good, and the presence of a defect such as a foreign material. Thus, in order to improve the yield, patterns on semiconductor wafers are inspected upon termination of each of the manufacturing processes so that the occurrence of an abnormality and the occurrence of a failure are detected early or in advance.
An inspection apparatus that is used for the aforementioned processes is required to execute inspection with high throughput and high accuracy since the diameters of wafers have been increased and circuit patterns have been miniaturized. To inspect many regions in a short time while the accuracy of the inspection is maintained, there is a method, as one of methods for inspecting a semiconductor device, for specifying a region located on a specified wafer beforehand, picking up images of multiple parts in one inspection, and inspecting the images.
A technique for detecting a defect in a circuit pattern formed on a semiconductor wafer is described in JP-2000-30652-A (Patent Document 1). A method described in Patent Document 1 includes imaging a wafer to be inspected to acquire an image of a pattern to be inspected that includes a defect and an image of a reference pattern that does not include a defect, and comparing the acquired images to extract parts different from each other as defects.
A technique for previously specifying a region to be inspected on a wafer is described in JP-2009-186328-A (Patent Document 2). Patent Document 2 describes a method for automatically detecting a region having a pattern with a desired repeating cycle on the basis of a variance and standard deviation of a differential image between an image having a repeating pattern and an image obtained by shifting the repeating pattern.
In addition, JP-61-140804-A (Patent Document 3) describes a technique for extracting a contour line from an image of a pattern to measure the width of the pattern, and comparing the measured width with design data or another actual pattern.